There are many types of headaches that afflict the human population. Migraine headaches cluster headaches, tension headaches and sinus headaches all cause serious pain and even disability. Moreover, migraine headaches occur in approximately 11% of the population in the U.S. and Western Europe each year, and more than 2.5 million persons in the U.S. have at least one day of migraine per week. Approximately 80 million additional people suffer from other types of severe headaches in the U.S. Although new drug therapies emerge each year, some patients cannot find relief with any existing drug therapy, and some therapies cause significant side effects. A non-invasive, non-drug method for preventing or treating migraine and other severe headaches would be a remarkable boon for those millions of people all over the world who suffer from these painful experiences.
Migraine is well known to be a neurovascular disorder that, in addition to pain, is characterized by autonomic nervous system dysfunction. Although the pain mechanisms are not well understood, it is believed that actions in nerves in the head, brainstem and other tissues cause blood vessels to dilate, which causes pain, which causes further nerve activation. In particular the trigeminal nerve and its associated autonomic nervous system function seem implicated in this process for migraine and cluster headaches. Disrupting this cycle can in some patients be a key to treating migraine and perhaps other forms of headache. It has also been demonstrated that magnetic (TMS) stimulation of the scalp causes alterations of the autonomic balance in the heart as measured by changes in the beat-to-beat variability of the heart.
Some patients with migraine experience a distinct aura or warning symptoms before the actual occurrence of the symptoms of the migraine headache. It is estimated that approximately 40% of all migraine patients have some type of aura that is a precursor of a migraine headache. Approximately half of these patients have a visual aura that typically begins as a small pattern of scintillating colored lights that have the appearance of wiggling worms or multicolored zigzags. Over a time period of between 20 and 30 minutes, the pattern enlarges and fades until it extends into the outermost portions of the visual field. During this time period, the patient might also completely lose part of his visual field. At the end of this visual aura, most migraine patients have a severe headache that is often accompanied by other symptoms such as nausea, vomiting and other unpleasant feelings. Many migraine patients who do not have a visual aura have some other precursor of a migraine that can be perceived from minutes to hours before the actual start of the headache. Special techniques may be used to treat patients with aura.
In 1985, A. T. Barker, et al (Lancet, 1985, pp. 1105-1107) described the use of an electromagnetic coil placed over the scalp which produced a high intensity, time varying, magnetic field. This magnetic field produces an electric current in the cortex of the human brain, which can in turn produce certain effects (e.g., depolarization and discharge) of brain neurons. This type of system has been given the name Transcranial Magnetic Stimulation (TMS). If repetitive magnetic pulses are applied in this manner, it has been given the name rTMS. In the journal Neurology (Apr. 11, 2000, pp. 1529-1531) it has been reported by B. Boroojerdi, et al, that rTMS at a rate of one pulse per second can-create a reduction of the excitability of the neurons of the human visual cortex.
In U.S. Pat. No. 6,402,678, which is included herein by reference, Fischell et al. describe the use of one type of system for the prevention or treatment of migraine headaches using one or more high intensity magnetic pulses that depolarize the neurons of the cerebral cortex. However, the Fischell et al patent does not describe specific systems and methods for stimulation of the trigeminal nerve and its associated autonomic nervous system function. Furthermore, the Fischell et al patent makes no mention of stimulation of the neck or the use of a system that has one portion of the system located on the patient's head or neck that is connected to a separate power source by electrical wires.